Here's a wierd one (a "bug") that I discovered while experimenting with typedefs and diagram terminals that you may want to try out (in LV7.0-7.1.1).
It's possible to create constants on the diagram that are impossible to remove. Here's how.
Create a typedef and place a constant of it on the diagram. Right-click on the constant and select "Advanced"..."Hide Control". Once you do you permanently have this typedef constant affixed to your VI. It isn't possible to move or select the typedef constant anymore and you can't delete it. You can still wire it however.
Bruce Moyer